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The requested URL /bookmarks/mark?op=add&bkmk=http%3A//stke.sciencemag.org/content/6/300/ra97&title=The%20Duration%20of%20T%20Cell%20Stimulation%20Is%20a%20Critical%20Determinant%20of%20Cell%20Fate%20and%20Plasticity was not found on this server. That’s all we know.